Screening genetic variation in maize for deep root mass in greenhouse and its association with grain yield under water- stressed field conditions

Plant roots have been recognized to play an important adaptive role in drought prone environments. There have been many efforts to improve root traits in order to develop drought tolerant cereal crops including maize but significant progress has not yet to be made. Twelve maize hybrids and their corresponding 12 female inbred par- ents were evaluated for genetic variation in deep root mass and other root traits in PVC tubes. The hybrids were selected based on their grain yield performance under water-stressed conditions in the field. Plants were grown in three different growing media, and a mixture of sand, vermiculite, perlite and soil was found to be the best growing medium to study root growth. Significant phenotypic variation was observed among inbred lines and among hy- brids for deep root mass (DRDW) and other related root traits under well-watered and water-stressed conditions. Based on individual hybrid comparisons and correlation analysis, deep root mass estimated in well-watered and water-stressed conditions in the greenhouse was found to be associated with grain yield under water-stressed conditions in the field. Hybrids with higher grain yield under water-stress showed considerable higher DRDW than the hybrids with lower grain yield. A conservation of the trait DRDW was observed between inbreds and hybrids as both groups exhibited similar patterns of variation. The current screening system for root traits is simple and in- expensive, making it useful for evaluating large number of inbred lines or hybrids for root traits under well-watered or water-stressed conditions for drought tolerance.